Field of the Invention
The present invention is related to a pneumatic tire designed for excellent performance in mud terrain and quiet ride on paved road.
Description of the Related Art
Japanese unexamined patent application publication No. 5-278415 discloses an all terrain pneumatic tire that comprises a tread portion provided with a circumferentially extending zigzag main groove and a plurality of broad shoulder lateral grooves extending axially outwardly from the shoulder main groove to form a plurality of shoulder blocks. In mud terrain, the respective shoulder blocks generate traction force by shearing large lump of mud pressed in the shoulder lateral grooves.
Unfortunately, the tire disclosed by the publication tends to produce a large pumping noise on paved road due to the air passing through the shoulder lateral grooves in a ground contacting patch of the tread.